(CBS) — A family who was attacked by a group of young people at Six Flags Great America in Gurnee during “Fright Fest” in September is suing the park for negligence allowing the attack to happen.

The Batavia family says Six Flags Great America staff failed to intervene when a group of about 20 young people attacked the 12-year-old boy and his parents at the park on Sept. 23, according to the three-count suit filed anonymously Monday in Cook County Circuit Court. The family suffered “extreme” and “debilitating” physical, emotional and psychological injuries.”

The three family members and the son’s friend were at the park for its Fright Fest Halloween-themed celebration when an unknown male wearing a Hawaiian shirt and shorts approached the son and his friend claiming to be security, according to the lawsuit. The male ordered the boys to follow him away from the more-populated area of the park.

The male showed false credentials to the mother and then tried to walk away when she confronted him, the suit alleges. The mother, who believed he was trying to lure her children away from her, followed the man, loudly yelling “security” for help.

The suit alleges that she was shouting from within eyesight and earshot of multiple Great America staff members, who “did nothing to intervene.”

A group of about 20 young males and females then started following the mother, yelling expletives and calling her a “snitch,” the suit alleges. She then returned to her husband, son and his friend, continuing to call for security.

Two of the people from the group then punched the son’s face, jaw and neck, according to the suit. The father tried to intervene and then was “viciously attacked.”

The group of young people appeared to be “beating and kicking [the father] to death,” according to the lawsuit. The mother threw herself on him to stop the attack and then was “repeatedly beaten and pummeled” by the group.

Great America employees allegedly still did not intervene in the attack, and a witness called 911, according to the lawsuit. At this point, the group stopped attacking and ran away.

Gurnee police reported that the attack stemmed from an argument when a group of teenagers cut in front of the family in line in the park’s Southwest Territory, near the Raging Bull and Giant Drop Rides.

The mother asked the group to stop using foul language, and one of the teens “sucker-punched” her son, according to Gurnee Deputy Police Chief of Operations Brian Smith. The parents stepped in, but the group overpowered them and continued to kick, punch and stomp them. They were taken to a hospital with “significant” injuries.

Gregory Battle, 18, was arrested in connection to the attack, police said. He was charged with aggravated battery causing great bodily harm, aggravated battery in a public place and mob action. The Waukegan resident was released after posting 10 percent of a $20,000 bond, according to Lake County Jail records.

Eight north suburban juveniles between 15 and 17 years old were also charged with mob action and taken to the Depke Juvenile complex Center in Vernon Hills, Smith said. Three of them face additional aggravated battery charges, and one was also charged with obstruction of justice for giving police a fake name. Their names were withheld because they’re minors.

The lawsuit accuses Six Flags Great America of negligence and seeks more than $150,000 in damages.

Representatives for Six Flags Great America did not immediately respond to a request for comment, but a spokeswoman for the park said in September the attack was “an isolated incident.”

The family requested to remain anonymous because the son suffers from a disability, they fear reprisals if their names go public and the incident was “highly personal and sensitive in nature.”

(Source: Sun-Times Media Wire copy; Chicago Sun-Times 2017. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)